Apparatus for fractionation



INVENTOR. M M

kMWEMREQ =1 W e I .6 .w

H. G. SMITH APPARATUS FOR FRACTIONATION Filed Dec. 18, 1920 PatentedJan. 20, 1925. p a

UNITED STATES PATENT OFFICE.

HERSCHIQL (3-. SMITH, OF SWARTHMORE, PENNSYLVANIA, 'ASSIGNOR TO THE AT-LAN'IIC REFININGCOMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TIONOF PENNSYLVANIA.

APPARATUS Fon FRACTIONATION.

- Applicationfiled-December 18, 192a Serial No. 431,552.

To all whom it may concern: 7 fuel and for mixture withlighter naphthasBe it known that I, HERSOHEL G. SMITH, for motor gasolene. My apparatusalso finds a citizen of the United States,-residing in application inincreasing the yield of gaso- 55 Swarthmore, county of Delaware, andState lene or other fraction of crude petroleum,

of Pennsylvania, have invented new? and having a given dry point orboiling point.

useful Improvements in Apparatus for For an understanding of myinvention Fractionation, of which the following is a and an illustrationof some of the various ifi ti n. forms my apparatus may take, referenceis 60 My invention relates to apparatus for h had th p y g e ga 1h 10fractional distillation of mineral oils or whlehi hydrocarbons, wherebyhigh selectivity as 1 l e e p y 111 e h, of pbetween diflerentfi'actionsor cuts is ob- 'e emhedylhg my 1I1Ve11t10 nt i bl d the by securing i aF1gs. 2 and 3 are vertical sectional views 65 of yield of a fraction orcut of desired charof lhedlfied forms of apparatus Whleh mayacteristics. be mp y d. v

In accordance'with my invention, the oil g- 4 1S elehm View, 011 largeScale, f containingthe desired cut or fraction'is y f Pe g e P ysubjected to distillation, yielding a mixture g to S represents Stlll 7of vapors ofoils of various boiling points, Whose contents y he mlsed t0a l th yapor i t b i Passed upwardly temperature by fire or other sourceof heat in heat transfermelation with downwardly external thereto, Steamh rged flowing condensate containing largely conf the Perforated P p tWhleh Steam densed vapors'of higher boiling point oils, in eenduetedfmgh the plpe 6. Or the 7 subdivided ,form or well distributed condi-'beefing of the stlll contents y be q tion, the extent or duration of theheat Rhshed y hethexterhel fihlhg end PP transfer relation being such asto yield tleh of Steam Wlthln h 111- sharply defined or selected cuts orfractions, The Vapors 0f h St111 are Conducted the degree of sharpnessor selection of a cut through t p P p 11118 V, In WhI h or fractionbeing controlled by maintainy he lheelted a thermometer to the 30 i itbl diff b t th t m chamber an the bottom of the tower structure of thevapor mixture from the still and ture eempnelhg the shell h Sheet' met31the vapor constituting the selected fraction 9 ether'ehltehle meterlehhaving edlaeeht or cut, such diflerence in temperature being pp end themanhole, f h e ee 85 procured or controlled by suitably conh upper d at9- h t fl with trolling diminution of the total heatcontent h hettelh ofthe ehalhhel' the e a i th Vapor i t pipe or l1ne D extend ng into theinterior In accordance with my invention,- the vat the stln: The t e e pe y Covered por mixture is cooled by bringing into con: Wlth heatlhshletlon, lhcheated 90 tact therewith condensate or liquid 'resu-lt-Aheve t ehemhelf d 15 the glflu 40 ing from the condensation of vaporsof the g e s above Whleh e filhhg h desired fraction or cut. or adistillate, liquid term? of t tower Sultahle helght, 15 h or condensateofsimilar, characteristics, and p h 7, efehy Sultable f r. Thls bycontrolling the quantity or temperature, p e eehetltutes numerous P 95or both, of thea'coolin'g condensate, the deh as vltlflfied earthenware,fermlhg e gree of sharpness of the desired cut is conmultitude oflhterstlees end Passagestrollable. As an example of various kindsandtypes My apparatus finds application in-the reof packing that may beemployed may be fining of petroleum, and particularly in mentionedvitrified tower packing such as 100 producing therefrom any sharplydefined used in manufacture or treatment of acid,

cut or fraction, as for example, sharply desuch as sulphuric acid. Suchpacking may fined fractionscf-n hthaandj kerosene or take any suitableform an example of which burning oil, the former utilizable for motor isindicated in Fig. 4, in which the external e, theliquid being deflectedfrom said walls into the packlng j. I

Communicating with the space or chamit ber 12 at the upper end of thetower is the pors flows through the pi vapor line or pipe V in which maybe inserted a thermometer c delivering vapors from the tower to thecondenser worm or coil C disposed within a tank or receptacle 1into-which cooling medium, as water, is introduced through the pipe 1'and carried off by the pipe 8. The condenser worm delivers through thepipe t into the receiving tank or condensate receptacle R from which thedistillatemay be drawn off through the pipe it.

Through the pipe *0 controlled by valve w, condensate or distillate maybe drawn from the tanlrl R by the pump at and delivered through themeter y to the pipe 2, which extends into the tower and delivers thedistillate to any suitable liquid subdividing means or sprayer, anexample of which is indicated at (L consisting of a tray receiving thedistillate from pipe 2 and havlng notches and openings for allowingescape of the distillate, by gravity, in small streams.

The operationis as follows:

Assuming it be desired to procure sharply defined cuts or fractions ofnaphtha and kerosene, there ma be charged into the still S petroleumdistil ate containing naphtha and kerosene. The still is heated or firedat suchvrate as to raise the charge to suitable temperature, whichtemperature may be increased at such rate as to effect the de-" siredrate of production of distillate or desired fraction. The mixture ofevolved vae V into the chamber d and thence upwar ly through theinterstices between and passages of the packingj, the vapors ofoils. ofhigher boiling points first condensing, and those of progressively lowerboiling points condensing at greater heights within the'tower V6, withthe result that there is an up-flowingstream of vapors and a downwardlyflowing stream of condensed oils of. boiling points higher than that ofthe desired fraction or final condensate or product of sharply definedfractionation, these heavier oils flowing back into the chamber (1 andthence through the runback D into the still S.

By this upward flow of vapors and counter or downward flow of condensedvapors, dephlegmation takes place, in that heat exchange occurs betweenthe rising vapors and descending oil, with the result that the vaporsreaching the upper end of the tower are those of oils having moreclosely the same boiling'points than the oils of the vapors delivered by"the still through the vapor line V; and the boiling points of the oilswhose vapors so reach the upperend of the tower e are lower than theboiling points of all the oils which are condensed within the tower andflow downwardly through the packing j. V

At thebeginning of the distillation the temperatures of thevaporsinthepipes V and V may notwidely difi'er; in fact, they may be but slightlydifferent, and thempors delivered 1nto the pipe V are those of naphtha,which are condensed in the coil G and delivered to the receiver B. Asthe distillation continues, the diiierencein temperatures registered bythethermometers c and c willfbe increased, particularly when there ispumped back through 'the pipe 2 to the spraying device a some of thedistillate from the receiver R, such" distillate constituting thedesired fraction or cut, i. e, the final product or final condensate;,At the beginning of application of the distillate to the sprayingdevice, the rate of delivery of the distillate may be small, andprogressively increased as the distillation proceeds. As the amount ofdistillate returned to the tower is increased, the difference. betweenthe temperatures registered by the thermometers c and 01 will increase,and at the end of the distillationperiod for procuring the naphthafraction or cut this temperature difference may amount to about degreesF. i

Thereturned distillate efiects an accentuated coolinglor chilling, inthat the distillate in descending through, the packing abstracts heatfrom the rising vapors, causing condensation therefrom of oils whoseboil ing points are higher than that of the desired distillate or cut,the returned distillate by the consequent absorption of heat beingvaporized, but the resultant vapors are those of the desired cut; andthey'againpass off. through the pipe V to the condenser C and return tothe receiver R as distillate along with additional distillaterepresenting part of the vapors affected within the tower e by thedistillate returning thereto.

The rate ofreturn of distillate to the tower is controlled, as by thevalve w, and by so controlling therate of supply of distillate to thetower, the distillation and shar fractionation are controlled. A ter theaforesaid naphtha cut has been taken, a similarly sharply I defined cutof kerosene or burning oil of desired characteristics may be taken insimilar way. After taking the kerosene out, there Will be left in thestill a residuum which is principally gas oil which may be utilized forother purposes.

The naphtha obtained in accordance with the above described method maybe employed as motor fuel, or may be mixed or blended with lighternaphthas, as casing head naphtha or gasolene, for producing motorgasolene.

In practicing the method as above described, the cost of fractionation,as measured in terms of heat units required or employed, is relativelylow, the only heat losses being those occasioned by radiation from theapparatus, as the tower, and the heat delivered to its cooling medium bythe condenser C. The heat loss in the condenser may be greatly reducedby using as the cooling medium delivered through the pipe 7' the oil tobe charged into the still S when such still is used in a. continuousdistillation process, as for example, when the still S is one of a 1series of two or more interconnected by pipes through which there isdelivered from one still, engaged in producing cuts of lower boilingpoint, oil or residuum to another still'of the series engaged inproducing a fraction of higher boiling point.

In Fig. 2 the arrangement is similar to that described in connectionwith Fig. 1. However, the lower end only of the tower e is covered byheat insulation h, and for the remainder of its height it is enclosed ina stack or shell A, spaced from the tower 6, air being admitted to thespace between the tower and shell through the inlet openings 6 Above thetower the stack is provided with a damper (1 whose position i 'controllable at will by the member e The upper end of the stack may beprovided with a removable cover 7.

The mode of operation is similar to that described in connection withFig. 1, though in this instance heat is abstracted from-the tower intothe air passing upwardly between the stack and tower 0. Control iseffected as described in connection with Fig. 1, by return of distillatethrough the pipe 2 into the tower, the distillate being returnedpreferably at least during part of the operation.

In Fig. 3 the tower e is open at its upper end,- whereby uncondensedvapors pass upwardly through the tubes 9 disposed within the shell Binto which air is admitted through the air doors h the air circulatingaround the tubes and passing upwardly through the hole 2' in thecircular header with which the upper ends of the aforesaid tubes 9communicate. The vapors of the desired fraction pass off from the headerthrough the vapor line V as before.

The air after contact with the tubes 9 passes oil' through the stack 76,the air'draft elng controllable by the damper m The mode of operation issimilar to that described in connection with Fig. 1, the vapors,however, being further differentiated or fractionated by thecondensation taking place in the air cooled tubes distillate beingreturned as before through the pipe 2, at least during some stage of theoperation.

By employment of the apparatus of Fig. 1, dephlegmation in addition tothat by the higher boiling condensate from the vapor mixture is securedentirely by re-introduction of distillate into the tower. In Fig. 2 theadditional dephlegmation is secured partly by the returned distillateand partly by radiation from the sides and upper part of the tower. InFig. 3 the additional dephlegmation is secured partly by returningdistillate, and partly by radiation from an air-cooled structure otherthan the tower.

While in the foregoing description reference has been made to return tothe dephlegmator of distillate constituting the desired fraction or cut,it will be understood that other suitable material or oil may beemployed, provided its characteristics are substantially similar tothose of the desired distillate.

The above described method and apparatus make easily attainable greatflexibility of control of conditions of distillation for a desiredsharply defined fraction; and the method and apparatus lend themselvesreadily to large capacity operations, since the. apparatus may beconstructed of any suitable or desired capacity.

lVhat I claim is:

Apparatus for producing a sharply defined fraction of petroleumcomprising a still, a dephlegmating tower, deflector members spacedvertically from each other in said tower and having their peripheries inliquid-tight contact with said tower, said deflector members extendingdownwardly and inwardly to openings, packing material in said towervertically continuous through said openings, a condenser, a vapor lineextendin from said tower above said packing to sai condenser, and meansfor returning from the outlet of said condenser to said tower above saidpacking condensate discharged by said condenser.

In testimony whereof I have hereunto affixed my signature this 16 day ofDecember, 1920.

HERSCHEL G. SMITH.

